1. Field of the Invention
The present invention relates to an apparatus with a gas sensor. The present invention especially relates to an apparatus with a gas sensor used for a fuel cell system driven by power from a fuel cell, specifically a fuel cell vehicle.
2. Description of the Related Art
Conventionally, there has been known a gas alarm including a gas tight housing having an inside channel and an inspection gas channel communicating the inside channel, in which an inspection gas is supplied to an inspection gas introduction part and then ejected from a nozzle of the inspection gas introduction part to the inspection gas channel, and therethrough reaches a gas sensor element disposed in the inside channel (see, for example, JP2005-202623A).
Such a structure is introduced to a fuel cell vehicle. The fuel cell vehicle is provided with a solid polymer type fuel-cell stack and a hydrogen tank under, for example, a floor panel, and with a hydrogen sensor configured to detect hydrogen leakage. Since hydrogen has a smaller specific gravity than that of air, the hydrogen sensor should be placed above the fuel cell system. In other words, the hydrogen sensor is attached to a lower face of the floor panel, which is above the hydrogen tank and the fuel cell. As a result, the hydrogen sensor is placed at a position where it is difficult to visually check the hydrogen sensor from outside the vehicle, and to access with hands or tools. Therefore, during maintenance of the vehicle, when the hydrogen sensor is to be inspected by spraying an inspection gas, there arises a problem of removing a part of components from the vehicle, leading to more complicated inspection work.
In order to solve this problem, there has been proposed a technique in which the inspection work is made facilitated by attaching piping to the vehicle in advance, which is configured to lead an inspection gas (calibration gas) to a vicinity of the hydrogen sensor from a distant position (see, for example, JP2006-329786A).
On the other hand, the fuel cell vehicle mounts various electric power devices configured to control high power, so as to obtain a driving force from a high-output motor. In addition, in order to prevent internal short-circuit (electrical short), the electric power device is encased in a sealed container for protecting from intrusion of foreign matters, such as water and debris. In the sealed container, a vent hole communicating with the atmosphere is formed, in order to prevent inner pressure fluctuation which may be caused along with the generation of Joule heat (see, for example, JP2007-20238A).
In addition, in the case where this electric power device is positioned under the vehicle interior, the electric power device directly suffers splash of water, mud, debris and the like from the road surface during vehicle running, and therefore it is desired that the vent hole be positioned as high as possible. Accordingly, in order to prevent the splashed waster, mud, debris and the like from entering the electric power device, it would be suggested that a breathing pipe which communicates with the sealed container, extends upward and has an upper end serving as a vent hole, be provided.
In the above-mentioned prior art gas alarm, it is necessary to include the inspection gas channel specially designed for passing an inspection gas, and the inspection gas introduction part specially designed for ejecting the inspection gas into the inspection gas channel. Further, in the fuel cell vehicle, in addition to the piping for these channels, it is necessary to install vent piping for the electric power device, leading to a problem that the structure of the fuel cell system becomes complicated and larger.
With respect to the vent piping for the electric power device, if droplets attach and accumulate inside the vent piping due to condensation or the like, water may flow to the electric power device or clog the breathing piping, which may deteriorate the prevention mechanism of the inner pressure fluctuation. Accordingly, in order to secure a performance stability of the electric power device, the breathing piping should be periodically cleaned, which lowers maintainability of the fuel cell vehicle.
Moreover, when such a hydrogen sensor is to be replaced, not only the hydrogen tank or the fuel cell stack locating thereunder should be removed, but also the inspection gas introduction piping, which requires longer working hours.
Therefore, it would be desirable to provide an apparatus which enhances efficiency of installing piping for supplying an inspection gas to the sensing element. It would be also desirable to provide an apparatus used for a fuel cell system which enhances performance stability of the electric power device and maintainability of the fuel cell system. It would be further desirable to provide an apparatus used for a fuel cell system having the inspection gas introduction piping, which improves workability in gas sensor exchange or the like.